this situation baffles me. i have a 1990 xj40 soverign with a quarter million miles. in the early morning and at night i can drive all over and back, but in the midday when its hot out i can make it about 30 miles and the car dies. will not fire imediatly. wait 4 min will start and run for half mile. wait 6 min it'll go for a mile. wait an hour and im good for another 30 miles. all guages are normal

 

Sounds like a fuel vapor lock issue to me. But let's see what some of the guys that have a little more knowledge chime in.

 

thats exactly the way it acts, but i didnt think that was possible on an fi engine. heck the last time i saw a vapor lock was a 74 maverick!

 

Loosen the gas cap, that should remedy the problem.

 

Have a look at this thread. https://www.jaguarforums.com/forum/s...ight=fuel+vent

 

tried that one already to no avail, thank you tho. definatly not building a vacuum in the tank.
is there a chance that a vcm code of fuel fail 37 is related?

 

Hopefully one of the tech guys can chime in.

Sounds like EGR related from the code, but don't know what to do about it.

I had to look it up, and I don't have EGR on the Euro XJ40.

 

As your problem happens only when its hot air temperature, the problem is heat related. I would check for fuel pressure (check when cold and then when car dies check to see if your getting pressure). If no pressure then check fuel pump, relays, and pressure valve. I assume that your fuel tank is venting as it should. Also make sure that your fuel filter is good (heat in summer and cold in winter do funny things to the filters.If you have fuel pressure when hot but car has died check for ignition, when the coil is weak they sometimes stop sparking and when they cool they will spark again (as the coil is mounted near the exhaust there is a lot of heat there). While checking it might be a good idea to put new plug wires (if you havnt done so already). I would also recomend getting a haynes or chilton manual makes chasing problems a lot easier.

 

Thank you. that gives me a few more ghosts to chase. already changed the fuel filter and wires. never thought of fuel presure or coil tho. i was gonna swap out the fuel pump next, but i didnt want to just keep easter egging parts without fixing the problem.

 

smog pump does not have a belt on it so not working. iv always assumed that was the cause of the check engine light. the code tho, not sure

 

As already mentioned, the fuel pump, it is probably the original, and 20 years old, and had a lot of fuel through it by now, and they dont last forever. Down here, about 100k milles is the average life, any car, makes not much difference??.

Could also be the pick up filter, inside the tank could be blocking up with crud, and the rest period allows that crud to settle a bit, engine starts, off you go.

The heat thing is also relevent to pump performance, which can drop off in an old pump as the fuel heats up.

 

as an update, swapped out the coil this morning and so far noticeable improvement. car fires instantly instead of turning over for 3 to five seconds prior to starting. going to drive to durango tonight bout 45 miles away. so well see if the coil was the culprit.

ok well not so good, made it bout 20 miles fore it died on me luckily about a mile from a friends house so got a ride to my meeting. guess im goin for the fuel pump on friday